Nac Tias had dark hair. He was somewhat tall when compared to the average of the other trainees from his squad. He wore the typical uniform of a member of the 104th Training Corps.
During the Battle of Trost District, Nac is assigned to the middle guard in Trost District. Shortly after the squad's deployment, the group is attacked by an abnormal Titan, which results in the death of Thomas Wagner. Eren Yeager is injured trying to avenge him, and the rest of the squad is killed trying to help Eren.
Armin would later report his demise to the remaining members of the 104th Training Corps, saying he died valiantly in the line of duty.